1. Field of the Invention
The present invention relates to new 1,3-dithiol-2-ylidene derivatives and salts thereof which exhibit excellent therapeutic and prophylactic effect for hepatic diseases, production methods of these compounds and pharmaceutical compositions containing theses compounds at a dose suitable for daily administration.
2. Description of the Prior Art
Diisopropyl 2-(1,3-dithiol-2-ylidene)malonate (malotilate) is a known hepatoprotectant described, for example, by Y. lmaizu-mi, et. al.,(Jpn. J. Pharmacol. 1981, 31(1), 15-21).
This compound and many closely related compounds and the preparation thereof are disclosed in U.S. Pat. Nos. 4,329,479 and 4,327,223, Spain ES 536,228 Ger Offen 2,625,012, Jpn. Kokai Tokkyo Koho 54-63,085 and 55-33,471 and Neth. Appl. 8,005,842. Dithiol derivatives having a ketone functional group in the side chain are disclosed in Jpn. Kokai Tokkyo Koho 59-42,377, 60-215,682, 61-275,274, and 62-158,274 and Eur. Pa 210,284.
Other 1,3-dithiol-2-ylidene derivatives containing an amide functional groups in the side chain are disclosed in Eur. Pat. Appl. EP 149, 534.